(Supported in part by the Princess Beatrix Funds no. 950501 to J.M. Trijbels) This is part of a Ph.D. thesis concerning defects in human mitochondrial transport processes, which cause myopathy. Two proteins involved in mitochondrial transport processes are the voltage-dependent anion channel, (VDAC), and the adenine nucleotide translocator, (ANT). Both VDAC and ANT are thought to be part of the "contact sites" between mitochondrial inner and outer membranes. We have embedded muscle material from patients deficient in VDAC and patients deficient in ANT ,as well as normal patients as a control. We hypothesize that the mitochondrial membrane structures may be changed when one of these proteins is not present or not functioning properly. The unique resources of the BMIRR offers us a chance to solve questions about the effects of deficiencies of particular transport proteins on the mitochondrial contact sites. We are hoping the results of this study will add new and useful information to our present understanding of the abnormalities in our patients. Two double-tilt reconstructions from 0.25lm thick sections were made, using the IVEM. Marjan Hiuzing visited Albany and traced membrane contours on slices from the reconstructions, using Sterecon. The contours were surface-rendered and color prints and video rotation-animations were made and sent to Marjan, as well as a CDROM. of the data. The VDAC-defecient mitochondrion had large, regular crystalline inclusions (believed to be creatine kinase) which were surrounded by two membranes which were apparently not continuous with the cristae membranes. The ANT-deficient mitochondrion had a large vacuole which pushed the cristae to the periphery. The cristae were vesicular and many were not connected to the inner membrane. Contacts between the inner and outer membranes were very rare in both mitochondria. The control specimen was not adequate, so we are waiting for another. The work was presented by Dr. Mannella at : Mannella, C. A., Buttle, K., Tessitore, K., Pixely, S., Gupta, M., Rath, B., D'Arcangelis, D., Marko, M. (1997) Workshop on New Perspectives in Mitochondrial Research, Univ of Padua, Italy, Spetember (sponsored by IUBMB, UNESCO and Ital Socty of Biochemistry).